Wireless system for preventing condensation on refrigerator doors and frames

ABSTRACT

The present invention is an improved anti-sweat controller for removing condensation from glass doors that are used on refrigerators in retail stores. The anti-sweat controller comprises three components, a sensor to measure condensation and temperature, a control unit to adjust door heaters, and a command unit. The sensors, control unit, and command unit all communicate on a wireless peer-to-peer network using the ZigBee protocol. Moreover, the command unit is attached to the Internet and enables a user to adjust the various settings on the anti-sweat controller from a remote location if desired.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and is a continuation-in-part ofco-pending application Ser. No. 10/778,289 filed Feb. 11, 2004 which ishereby incorporated herein by reference.

FIELD OF INVENTION

This invention relates generally to refrigeration devices. Thisinvention relates particularly to a wireless device for reducing energyconsumption by refrigerator door and frame heaters while maintainingprotection against condensation.

BACKGROUND

Shopkeepers display refrigerated or frozen products intemperature-controlled display cases, such as refrigerators with glassdisplay doors or open-air, “coffin,” coolers. The refrigerators andfreezers are referred to herein as “refrigerators.” Changes intemperature and humidity in the surrounding area cause condensation andfrost to build up on the refrigerators. This obstructs visibility of theproducts and can cause unsafe conditions as the condensation falls tothe floor. As a result, it is desirable to prevent the build-up ofcondensation and frost on refrigerators.

To combat condensation and frost, heaters are installed in refrigeratordoors and frames, which raise the temperature of the door or framesufficiently to eliminate condensation. Typically these heaters runconstantly, but devices that control whether the heaters are on or offare known in the art. They are referred to generally as anti-sweatcontrollers. One anti-sweat controller known in the art attaches one ormore condensation sensors to the refrigerator door or the frame andturns on a door heater when condensation is sensed. Traditionally, asingle control box is used to control all the sensors of a givenrefrigerator. These devices fail, however, to prevent condensationbecause the heater is not activated until after condensation is sensed.Another version uses a humidistat to sense humidity in the aisle and,when the humidity goes above a given level, the heater is turned on,often regardless of whether condensation is actually present. Thisincreases energy consumption because the heater is either constantly onor turned on unnecessarily. It would be desirable to preventcondensation with the minimum amount of heat, and consequent energyexpenditure, necessary.

Known anti-sweat controllers connect the control box to the sensors withwires that transmit and receive data between the sensors and controlboxes. For example, if a sensor detected a certain level of humidity onthe refrigerator door, the sensor would transmit a signal through thewire to the control box directing that the control box turn the heateron to remove humidity and associated condensation from the door.Hardwiring the various sensors to the control box is problematic as itincreases the time needed to install anti-sweat controllers.Additionally, the wires can be accidentally cut which results in anon-functioning anti-sweat controller which may require a qualifiedrepairman to fix. It would be desirable to provide an anti-sweatcontroller that utilized wireless sensors to communicate with thecontrol box to eliminate these communication wires.

Additionally, anti-sweat controllers are also hardwired into the localpower source, which results in difficult access for repair andreplacement because the anti-sweat controllers must be unwired each timethey are removed and rewired each time they are reinstalled. If theanti-sweat controller breaks, the fact that the system is integral withthe local power source may cause the shopkeeper to be unable to set thesystem to keep the heaters on until a qualified repairman fixes theproblem. Further, the dismantling and reconstruction cause safety issueswhile obstructing customer access to the refrigerators. It would bedesirable to provide an anti-sweat controller that is connected to thepower source with a quick-disconnect plug enabling it to be easier toinstall, repair and replace and that provides a means for the shopkeeperto mitigate problems if a controller fails.

The controller box controls a number of factors that must be setcorrectly to reduce energy consumption and eliminate condensation, suchas sensitivity of the sensor and how long the heater stays on or offonce signaled. To date, these factors have been measured and controlledby manually adjusting various currents and voltages on each control boxwith a multimeter. For a store with multiple refrigerators and multipleanti-sweat controllers, the multimeter must be plugged into eachseparate controller in order to adjust the entire system. Detecting thespecific location of an electrical failure is frustrating and timeconsuming due to the need to test each separate device. Balancing thesystem becomes tedious. As a result, it is desirable to reprogram,monitor, and control an anti-sweat controller system without having toplug into each control box on each refrigerator and without having tomake on-site visits to each store. Specifically, it would be desirableto provide a control box that could be programmed from a remote locationusing the Internet.

Therefore, it is an object of this invention to provide an anti-sweatcontroller that operates a heater where condensation has not yet beendetected but is anticipated. It is another object of this invention toprovide ease of programming, repair, and reinstallation by providing ananti-sweat controller with sensors and control boxes that communicatewirelessly. It is a further object to provide a system that can be setto a heater-on state if a problem arises with the anti-sweat controller.It is an additional object of the invention to provide remote monitoringand control of an anti-sweat controller over the Internet.

SUMMARY OF THE INVENTION

The present invention is a device for reducing energy consumption ofheaters on refrigerator doors and frames. A control unit is set so thatthe heater is on prior to the formation of condensation. The preferredembodiment provides a door heating system that only turns on the heaterwhen condensation is present to conserve energy. The heater may also beturned on when condensation is sensed by a sensor, and the sensorreading may be used to override the preset times. The control unit andsensors are capable of transmitting and receiving data wirelessly whicheliminates the need for hardwiring the sensors to the control units. Inthe preferred embodiment, a command unit is used to enable remotemonitoring and control of the control units and sensors and communicateswirelessly with the control units and sensors. The command unit isconnected to the Internet to enable a user to monitor and control theanti-sweat controller from a remote location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an anti-sweat controller installed on a refrigeratoraccording to the present invention;

FIG. 2 illustrates a control unit according to the present invention;

FIG. 3 is a block diagram of the command unit; and

FIG. 4 illustrates the anti-sweat controller including the sensorinstalled on a single refrigerator door and the control unit which arein operative communication with the command unit.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-4, the system comprises a control unit 110, one ormore sensors 114, and preferably a command unit 120. The system is usedto prevent condensation on the doors and frames of a refrigerator 111 inconjunction with a heater (not shown, but usually incorporated in thedoor or on the frame) and a control unit power source 115. Control unit110, sensors 114 and command unit 120 are each equipped with atransceiver 113 to receive and transmit data wirelessly. Control unit110 is typically located apart from the door heaters and may operatemultiple doors. In the preferred embodiment, the control unit operatesapproximately four heaters on four different refrigerator doors orframes. Control unit 110 communicates with the command unit 120 and oneor more sensors 114 on the wireless network and is connected to controlunit power source 115. In the preferred embodiment, command unit 120 isconnected to an information technology network and is capable oftransmitting data gathered from control unit 110 and sensors 114 overthe Internet to a user such as a shopkeeper who can then monitor andadjust control unit 110 and sensors 114 from a remote location.

In contrast to prior art anti-sweat controllers which relied on discreteand analog components, the present invention utilizes integratedcircuits and digital transmissions for increased sensitivity, control,and reliability. For ease of installation with known performancecharacteristics, control unit 110 preferably uses modular connectorsknown in the art to connect to the various door heaters. Control unit110 can usually control up to six door heaters, therefore, if aparticular store has more than six heaters, additional control unit(s)110 may be needed. Control unit(s) 110 preferably further comprises acomputer processor 160, preferably a custom-programmed microcontrollerthat includes a timer, memory and an analog-to-digital converter. Apreferred microcontroller is available from Freescale Semiconductor,Inc. of Austin, Tex. and sold as part number MC9S08GT60. Control unit110 is capable of being programmed to turn the heaters on and off atcertain times.

While control unit 110 is hard-wired to the heaters to deliver power tothe heaters, control unit 110 communicates wirelessly with sensors 114,command unit 120, and, if present, other control units 110. As shown inFIG. 1, an electrical wire 112 connects control unit 110 to othercontrol units 110. Control unit 110 is also equipped for wirelesscommunication with known wireless communication equipment including thecustom-programmed microcontroller on a wireless peer-to-peer network ora star topology physical network using the Zigbee protocol.

As shown in FIGS. 1 and 4, sensors 114 are attached to the refrigerator,positioned uniquely for each refrigerator where condensation forms thesoonest, such as on the door jams, headers, or mullions. In thepreferred embodiment, the sensors are located on the door frames.Sensors 114 are capacitive sensors in the preferred embodiment andcapable of detecting both relative humidity levels and temperature. Eachsensor 114 is equipped to communicate wirelessly on the peer-to-peer orstar topology network of other sensors 114, control unit(s) 110 andcommand unit 120, preferably using a ZigBee protocol network.Specifically, sensors 114 receive wireless data from control unit 110.In this embodiment, sensors 114 are adjusted by sending data throughcontrol unit 110 which in turn adjusts sensors 114. However, sensorscapable of individual adjustment without requiring control unit 110could certainly be used and fall within the scope of the presentinvention. An example of an acceptable sensor is a Humerel® sensorproduced by Measurement Specialist, Inc. of Hampton, Virginia.

Control unit 110 receives data wirelessly from sensors 114 related to aparticular door's temperature or the humidity within a refrigerator andcompares that data to thresholds contained within a database. If acertain temperature or humidity threshold has been reached at a specificdoor or refrigerator, control unit 110 will direct that the heaterassociated with that refrigerator turn “on” until the humidity andtemperature level are restored to acceptable levels. The times thatcontrol unit 110 directs certain heaters to turn on can be adjusted bysending wireless commands to control unit 110 from command unit 120 asdescribed below or they can be adjusted using a personal data assistantor PDA device that is equipped to receive and transmit data on theZigbee protocol directly to control unit 110.

Command unit 120 is generally located apart from the refrigerator doorsand communicates with the various sensors 114 and control unit 110 toenable a user to adjust certain thresholds or settings within controlunit 110 and sensors 114. Command unit 120 is connected to a computer121 (preferably a personal computer) by an Ethernet connection in thepreferred embodiment and enables a user to adjust control unit 110thereby adjusting sensors 114 or the heaters. This adjustment can bemade at computer 121 or at another computer via the Internet if computer121 is connected to the Internet.

As shown in FIGS. 3, command unit 120 comprises a microcontroller 80,command unit power source 82, transceiver 113, and memory 84.Microcontroller 80 preferably includes an integrated Ethernet MediaAccess Controller and 10/100 Ethernet Physical Layer and on-chip flashmemory. In the preferred embodiment, microcontroller 80 is customprogrammed for this specific application as known in the art. Anacceptable microcontroller 80 is available from Freescale Semiconductor,Inc. and sold as part number MC9S12NE64. To protect the variouscomponents from damage, command unit 120 can include a housing. Anacceptable housing is available from Hammond Manufacturing ofCheektowaga, N.Y. and sold as part number 1593X. Additionally, commandunit power source 82 can either be batteries or alternating current thathas been adjusted by a transformer such as a wall wort.

Command unit 120 adjusts various values via control unit 110, such aslowering the set point of sensor 114 and thereby decreasing sensitivity.For example, if the set point of a particular sensor 114 is set high,such that the heater is instructed to turn on when very little humidityis present, the heater will turn on as the lightest condensation occurs.However, if the sensitivity is set lower, such that the heater turns ononly when significantly more humidity is measured, the heater will turnon when more condensation is present. Ideally the sensitivity isadjusted to maintain an optimum balance between condensation and theamount of time the heater is on. Of course, the less the heater is on,the less energy is consumed by the system and the lower the energycosts. Command unit 120 is also used to set start and stop times, asdiscussed in more detail below, which work in cooperation with thesensor setting. Proper settings enable the shopkeeper to achieve demandsavings, i.e., reducing power consumption during higher-rate periods, aswell as savings due to overall power consumption.

To anticipate condensation, the control unit 110 signals when the heatershould be on prior to the formation of condensation, for example, atpreset start and stop times consistent with when condensation isanticipated. For example, in the context of supermarket refrigeratordoors, preset start times could be set to once every hour, on the hour,between 6 a.m. and 9 a.m., 12 p.m. and 1 p.m., and 5 p.m. and 9 p.m.(times corresponding to when the supermarket is very busy, refrigeratordoors are repeatedly opened, and condensation is anticipated).Preferably preset stop times are set to provide for 15 minute dutycycles. These preset times work in cooperation with sensors 114, and thesensor 114 measurements can override the preset times. For example, inthe event the pre-set cycle time is insufficient to preventcondensation, the sensor reading can override the pre-set “off” time andcause the heater to run until no more condensation is detected. Computer121 is equipped with software which is used to adjust the various presetstart and stop times of the control unit 110. Data entered on computer121 by a user (such as a shopkeeper) is sent to command unit 120 andthen wirelessly transmitted to control unit 110.

A quick-disconnect coupling 140 connects each control unit 110 to thecontrol unit power source 115. Coupling 140 is preferably a mate andlock connector, with four prongs 143, as shown in FIG. 2. Otherquick-disconnect plugs that provide simple, rapid separation of thespliced wires without the use of tools may be used. Coupling 140 enablesa shopkeeper to disconnect the control unit 110 from the heaters withoutunwiring the system, which allows the heaters to revert to theiralways-on state and prevent condensation until a qualified repairman canfix the system. Alternatively, the heaters can be turned completely off.Coupling 140 also provides for a control unit 110 to be removed andinstalled much more safely and quickly than prior art devices. Controlunit power source 115 is preferably an AC power supply, such as acircuit off of the mains.

While command unit 120 isn't necessary for the anti-sweat controller tofunction, it is used in the preferred embodiment to enable a user toeasily monitor and adjust control unit 110 and sensors 114 from a remotelocation. As noted above, command unit 120 is capable of receiving datafrom control unit 110 and sensors 114 and storing the data in adatabase. Computer 121 can transmit that data over the Internet to anyother computer that is connected to the Internet. In the preferredembodiment, a shopkeeper would be able to review the data in thedatabase on the Internet. The shopkeeper could view data collected inthe database relating to the various times that the heaters turned onand off to reduce humidity and condensation within the refrigerator andmake adjustments if necessary. The ability to adjust the various heatersand review the data collected in the database is greatly simplifiedsince the control unit 110, sensors 114, and command unit 120communicate on a wireless network.

While any wireless communication standard can be used and fall withinthe scope of the present invention, the IEEE 802.15.4 standard (commonlyknown as a ZigBee wireless network) is preferred. In this regard, datais sent in packets to and from the respective transceivers 113 on thecontrol unit 110, sensors 114, and command unit 120. The IEEE 802.15.14standard for Wireless Medium Access Control (MAC) and Physical LayerSpecifications for Low-Rate Wireless Personal Area Networks (LR-WPANs)is available from the Institute of Electrical and Electronics Engineers,Inc. of New York, N.Y., and is herein incorporated by reference. Othershort-range, wireless networks could be used and fall within the scopeof the present invention including a Bluetooth wireless network.

The advantages of the anti-sweat controller of the preset invention canbe illustrated by the following example. In a store with approximately10 refrigerators, the control unit(s) 110 may be set to turn the heaterson at peak times, at 7:30 A.M. and 5:00 P.M. and cycle the heaters for a15 minute interval. Throughout a given week, five out of ten heaters areonly activated at that preset times as the humidity and temperaturelevels in those refrigerators are below the thresholds programmed intocontrol unit 110 for sensors 114 to activate the heaters. But, thehumidity and temperature within the remaining five refrigerators doesreach the particular threshold directing that sensors 114 send signalsto control unit(s) 110 to turn on the door heaters to remove thecondensation from the door. The control unit(s) 110 transmits wirelessdata related to the time that the heaters turned on and the durationthat they were on to command unit 120 which transfers this data into thedatabase.

Since command unit 120 is connected to computer 121, this data isavailable to be accessed over the Internet. The shopkeeper can log ontothe database via the Internet and view that data which shows that theheaters are being activated for five out of the ten refrigerators at3:00 P.M. Monday-Friday during the week. Upon reviewing this data, theshopkeeper decides to modify the settings for the heaters in the fiverefrigerators so that they are activated a 2:50 P.M. in an effort toprevent condensation before it is likely to form. The shopkeeper simplymakes the adjustment on a computer which is sent over the Internet tocomputer 121 which in turn transmits this adjustment data to commandunit 120. Command unit 120 wirelessly transmits this adjustment data tocontrol unit(s) 110 which are programmed to turn on the heaters at 2:50P.M. in addition to the normal times of 7:30 A.M. and 5:00 P.M.

Therefore, the shopkeeper can monitor and control the anti-sweatcontrollers for a given store in any location where Internet access isavailable. Moreover, the number of anti-sweat controllers that can bemonitored in this fashion is unlimited. Therefore, a shopkeeper canmonitor the door heaters in a single store or dozens of stores indifferent locations if he so desires. Additionally, because theanti-sweat controller's operation can be monitored via the Internet, itis easier to diagnose if a problem exists. For example, if a heaterfails, a shopkeeper can view the data about the operation of theanti-sweat controller and easily determine which heater ismalfunctioning.

While there has been illustrated and described what is at presentconsidered to be the preferred embodiment of the present invention, itwill be understood by those skilled in the art that various changes andmodifications may be made and equivalents may be substituted forelements thereof without departing from the true scope of the invention.Therefore, it is intended that this invention not be limited to theparticular embodiment disclosed, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A system for reducing energy consumption by a heater on arefrigerator door comprising: a) a control unit comprising a computerprocessor having memory and a timer, the control unit connected to theheater; b) a sensor attached to the refrigerator door that sensesrelative humidity and directs that the control unit turn on the heaterwhen condensation is likely to be on the refrigerator door; d) whereinthe sensor and control unit are equipped with wireless communicationdevices that enable them to transmit and receive data.
 2. The systemaccording to claim 1 further comprising a command unit that communicateswirelessly with both the sensor and the control unit.
 3. The systemaccording to claim 2 wherein the command unit is connected to theInternet and capable of transmitting data from the sensor and controlunit over the Internet to a user.
 4. The system according to claim 3wherein the user can control and adjust the sensor and heater at acomputer connected to the Internet that receives data from the commandunit.
 5. The system according to claim 2 wherein the sensor is acapacitive sensor.
 6. The system according to claim 2 wherein the sensoris capable of sensing temperature as well as humidity.
 7. The systemaccording to claims 2 wherein the sensor, control unit, and command unitcommunicate on a ZigBee wireless network compliant to the IEEE 802.15.4standard.
 8. A system for reducing energy consumption by a heater on arefrigerator, the system comprising: a) a heater; b) a control unitconnected to the heater that turns the heater on and off atpredetermined times and transmits and receives data wirelessly; c) atleast one sensor that senses the presence of humidity or a change intemperature that transmits and receives data wirelessly; d) a commandunit that transmits and receives wireless data from the control unit andat least one sensor; and e) a first computer connected to the commandunit that transmits the data received from the control unit andsensor(s) to a second computer over the Internet.
 9. The system of claim8 wherein the user can control the heater and adjust the predeterminedtimes that the heater turns on and off by using the second computer totransmit data over the Internet to direct the control unit to adjust thepredetermined times when the heater is turned on and off.
 10. The systemaccording to claim 8 wherein at least one sensor is a capacitive sensor.11. The system according to claim 8 wherein the heater and at least onesensor are located on the same refrigeration compartment door.
 12. Thesystem according to claim 11 further comprising additional refrigerationcompartment doors, each of which contains a separate heater and at leastone sensor.
 13. The system according to claim 12 wherein the commandunit receives data from the control unit and at least one sensor on allthe refrigeration compartment doors.
 14. The system according to claim 8wherein the at least one sensor, control unit, and command unitcommunicate on a wireless peer-to-peer network.
 15. The system accordingto claim 8 wherein the command unit transfers the data received from theat least one sensor into a database.
 16. A method for remotelymonitoring and controlling refrigerator door heaters comprising: a)providing a first group of refrigeration compartments with at least onedoor wherein each door comprises a heater and a sensor that is capableof wireless data transmission to and from a control unit; b) providing afirst command unit that communicates wirelessly with at least one sensorand control unit; c) connecting the first command unit to the Internet;d) using the first command unit to transmit data from the control unitand at least one sensor over the Internet to a computer operated by auser; and e) enabling the user to adjust the heating system from aremote location by transmitting commands entered by the user at thecomputer to the first command unit over the Internet.
 17. The methodaccording to claim 16 further comprising: a) providing a second group ofrefrigeration compartments in a different location than the first groupof refrigeration compartments, wherein each door comprises a heater anda sensor that is capable of wireless data transmission to and from acontrol unit; b) providing a second command unit that communicateswirelessly with at least one sensor and control unit on the second groupof refrigeration compartments; c) connecting the second command unit tothe Internet; d) using the second command unit to transmit data from thecommand unit and at least one sensor located on the second group ofrefrigeration compartments over the Internet to a computer operated by auser; and e) enabling the user to individually adjust the heating systemin either the first or second groups of refrigeration compartments froma remote location by transmitting commands entered by the user at thecomputer to the first and second command units over the Internet. 18.The method according to claim 16 further comprising the step ofproviding a database that collects and stores data related to theoperation of the control units and sensors that the user is able toaccess over the Internet.
 19. The method according to claim 17 furthercomprising the step of providing a database that collects and storesdata from the first and second command units that the user is able toaccess.
 20. The method according to claim 16 wherein all the wirelessdata transmission occurs on a ZigBee wireless network compliant to theIEEE 802.15.4 standard.
 21. A method for remotely monitoring andcontrolling refrigerator door heaters comprising: a) providing a firstgroup of refrigeration compartments with at least one door wherein eachdoor comprises a heater and a sensor that is capable of wireless datatransmission to and from a control unit; b) providing a first commandunit that communicates wirelessly with at least one sensor and controlunit; c) connecting the first command unit to the Internet; d) using thefirst command unit to transmit data from the control unit and at leastone sensor over the Internet to a computer operated by a user; and e)enabling the user to verify that the system is operating properly and tocorrectly identify whether a particular component is malfunctioning.